In order to improve the wiping quality obtained by means of a wiper blade, made from natural or synthetic rubber or elastomer, it is known how to provide it with a coating comprising a powder, in particular crystalline carbide in the form of natural or artificial graphite, containing lamellar particles of very small dimensions. These particles have a lamellar structure, which enables them to have a function equivalent to that of a “lubricant” for significantly improving the wiping quality.
It is known how to produce such a coating by means of a solution consisting essentially of a binder, in the form of an acrylic, vinyl or styrene or urethane resin in which the graphite powder is dispersed.
The coating is produced by soaking the blade in the solution or by coating the blade by means of the solution, and then drying.
Such a coating, though it makes it possible to improve the wiping quality, has the drawback of giving rise to certain unpleasant phenomena (turning over, squealing etc) when the glazed surface is not very moist, also referred to as “drying window”.
These phenomena are non-existent when the window is wet since a film of water is always present between the window and the wiper blade, and this film of water also acts as a lubricant. In the “drying window” phase or when wiping dry, the absence of the film of water causes an increase in the coefficient of friction between the window and the wiper blade, and hence the unpleasant phenomena.
In addition, such a coating has the drawback of not being able to be coloured because of the presence of graphite. This is because graphite is black in colour and the proportion of graphite in the solution is around 30% by weight. Thus the proportion of pigments necessary for obtaining a colouring of the coating would be too great and might impair the quality of wiping.